Yep yesterday was a truly bizarro day wind wise. The Gorge having unheard of EAST winds at The Wall with gusts to 30 knots. And Crissy, which most forecasts had pegged as a heat wave day, saw WEST winds gusting to 40 knots and deep fog.

Basically, as George said, the Gorge had strong easterly winds way aloft from a clockwise spinning high pressure north of the Gorge.

While way aloft over California a counter-clockwise spinning Cut-Off Low created more easterly wind near the Gorge. But over the Bay Area that meant WSW winds aloft. It also induced at the surface a strong counter-clockwise spinning low pressure which created a powerful pressure gradient to the California Central Valley.

Take a look at the animation at the bottom and notice how the 2 winds aloft merged over the Gorge. To get oriented study the annotated imagery at the bottom to see this bizzaro pattern unfold.

I think I have only seen this pattern in the late fall when we get a short wave dropping over the ridge. Even then it seems to set up like this pretty rarely. Thanks for the nice graphics Mike and Ben. A picture is worth a thousand words!

You have to remember that this video and the previous one are water vapor images. They only show the wind induced cloud movement from 10K feet and above NOT the surface wind. Yesterday and today the upper level winds are easterly while west winds rip at the surface in the How can this be?

Well, the atmosphere is like a giant layer cake. Sometimes the layers interact and sometimes they are decoupled. Today they are decoupled, the bizarro east wind....coupled. Things like this make forecasting models and forecasters have less than stellar accuracy.

Today's winds actually are partially caused by those East wind aloft. There is a huge upper high pressure above the Pacific Northwest which has been creating all the warm weather. High pressures like this have clockwise spinning winds and we are below the East wind zone. This east wind aloft is not impacting us but all the heat from the high pressure aloft has set up at the surface a low pressure zone. You can see this in the graphic below with the low pressure in the Columbia Basin and high pressure from the North Pacific High and cool dense marine layer air to the west.

Hope this makes sense. Check out the Weather Blog link to the right for more articles.

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